A typical flash memory device may comprise a memory array that includes a large number of non-volatile memory cells arranged in row and column fashion. In recent years, vertical memory, such as three-dimensional (3D) memory has been developed in various forms, such as NAND, cross-point, or the like. A 3D flash memory array may include a plurality of memory cells stacked over one another. Each group of memory cells may share a plurality of access lines, known as wordlines (WLs) and bitlines (BLs).